What angle is this is it a obtuse right or straight I need help

Anne found the 10th term of the following sequence. her steps are shown below. 3, 7, 11, 15, … 1. common difference = 4, a1 = 3 2. an = 3 + (n - 1)4 3. an = 3 + 4n - 4 4. an = 4n - 1 5. a10 = 4(10) – 1 6. a10 = 39 analyze anne’s work. is she correct? if not, what was her mistake? yes, she is correct. no, she needed to find the common ratio because it is a geometric sequence. no, she substituted the wrong values into the rule to find the equation that represented the sequence. no, she solved for the 10th term incorrectly.